//实现动画下拉的input的插件代码
;(function($){
jQuery.fn.slideArea=function(options){
       options=$.extend({height:80,element:".app_textarea_d",isClear:true,needAnim:true},options||{});
       return this.each(function(){
             var $_slideEle=$(this);
             var old_height=$_slideEle.height();
             if(old_height==0){
                old_height=$_slideEle.css("height");
             }
             var old_value=$_slideEle.val();
             var old_color=$_slideEle.css("color");
             $(this).focus(function(){
               if(options.isClear){
                if($(this).val()===old_value){
                     $(this).val("");
                  }
               } 
                   if(options.needAnim){
                      $(this).animate({height:options.height},{duration:"fast"});
                   }else{
                      $(this).css("height",options.height); 
                   }
                  $_slideEle.css("color","#434343");
                  $(this).addClass("app_textarea_focus");
             }).blur(function(){
                if($(this).val()===""){
                    if(options.needAnim){      
                      $(this).animate({height:old_height},{duration:"fast"});
                    }else{
                       $(this).css("height",old_height);  
                    }
                   if(options.isClear){ 
                      $(this).css("color",old_color).val(old_value);
                    }
                 }
                 $(this).removeClass("app_textarea_focus");
             })         
        })
    }
})(jQuery);
;